X-ray tube



VIVavrch 2l, 1933. w HQFMANN 1,902,502

X-RAY TUBE v Filed June 6, 1931 Ob/ec subJeced to X rays.

by l

His Attovey.

Patented Mar. 2l, 1933-v UNITEDSTATES PATENT OFFICE WALTER HORMANN, or ERLANGEN, GERMANY, AssIGNOR To GENERAL COMPANY, A CORPORATION on NRW YORK ELECTRIC X-RAY TUBE Application filed June 6, 1931, Serial No. 542,671, and' :ln lGermany February 4, 1930.

v In the case of X-ray tubes provided with an Y this disadvantage is eliminated by increasing the intensity of the electron bombardment of the anode in proportion to the distance ofthe point -of impact from the axis of rotation.

One method, for example, of bringing about this result is to diminish the distance between the turns of the heated filament in inverse proportion to their distance from the axis of rotation.

Inthe form of construction shown by way of example in the accompanying drawing, the rotating anode 1 is arranged to turn on its longitudinal axis by means of well known devices. The cathode comprises the focussing device 2 and the spirally shaped, heated lament 3. The distance between the respective turns of the filament decreases from they right to the left as shown, thus causing an increase in electron emission as the outer end of thevlament is approached. Consequently, the intensity of the bombardment of the anode becomes greater from the inner edge to the outer edge of the area ofimpact 4.-. In view, however, of the greater peripheral speed of the outer edge, the difference in the terminal load is substantially compensated.

What I claim as new and desire to secure by Letters Patent of the United States is: 1. An X-ray tube including an envelope 40 and provided with an anode adapted to rotate, and a line focus cathode, said cathode comprising a helical filament whose turns areAv l spaced closer togetheras the end of the filament remote :from theanode axis of rotation is approached.

tate and an electron emitting cathode, said 2. An X-ray tube including` an envelope l vand provided with an anode adapted to rocathode being adapted to emit electrons in increasing numbers'as the portion of the cathode remote from 'the anode axis of rotav tion is approached. Y

3. An X-ray tube including an envelope and provided with an anode adapted to rotate, and a line focus cathode, said cathode comprising a helical filament vwhose turnsV are spaced `continuously closer together in proportion to the relative distances of the respective turns from the anode axis of rotation. v Y Y Y Y 4. An Xfray tube including an envelope and provided with an anode adapted to ro-v tate, and a line focus cathode, said cathode comprising a helical filament, the spacing between the turns being inversely proportional to the linear speed corresponding to the distance of the turn from the anode axis of ro-VY tation.

In witness whereof, I have hereunto set my hand.v

WALTER vao 

